Through Jeff's lens, we see images of all kinds of male-female relationships. From the distant views of the squabbling older couple and the sad exploits of Miss Lonelyhearts to the close-ups of Grace Kelly's amorous come-ons, the film explores an entire range of relationships through visual imagery. Jeff and Lisa's relationship is the only one that gets dialogue and exposition; everything we know about the others comes from what we see through Jeff's eyes. It's amazing when you think about how much we know about the newlyweds or Miss Torso or the unhappy Thorwald marriage just from our glances into their apartments.
One writer thought that Rear Window was really a story about relationships just cleverly disguised as a murder mystery: "All of the lives Jeff observes from his rear window have one common denominator; they all in some way reflect different aspects of love and relationships. They all have a bearing on Jeff's view of love and marriage." (Source) In this view, the murder was just a plot device for the development of the complicated relationship between Jeff and Lisa.
Hitchcock gives us his final ambiguous prediction about that relationship using visuals: Lisa lounges on Jeff's daybed, but this time, she wears jeans and loafers and reads a travel book. Looks promising, right? But wait, there's more. Once she sees he's asleep, she puts down the travel book and picks up a copy of a fashion magazine.